Arc-lamp electrode



FILED JUNE 11, 1919- 11v VENTOR H.B. EYNDN ATTORNEY Patented Feb. 13,1923.

UNITED STATES st w:

PATENT ource.

HOWARD B. EYNON, OF LAKEWOOD, OHIO, ASSIGNOB '10 NATIONAL CARBONCOMPANY, INC A CORPORATION OF NEW YORK.

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Application filed June 11, 1919. Serial No. 808,802.

To all whom it may concern.

Be it known that I, HOWARD B. EYNON, a citizen of the United States,residing at Lakewood, in the county of Cuyahoga and State of Ohio, haveinvented a certain new and useful Improvement imArc-Lamp Electrodes, ofwhich the following is a full, clear, and exact description.

This invention relates to an improvement in arc lamp electrodes, andparticularly tonegative electrodes especially adapted for use inprojectlon apparatus.

' One of the most important requirements which must be fulfilled forthis type 0f service is arc steadiness, and my invention relates to, andespecially discusses an electrode structure which satisfies thisparticular requirement.

I have found that the arc has a very strong tendency to spring from thehottest part of a negative electrode and to remain there. I have foundthis to be especially true in the case of pure carbon electrodes or withelectrodes in which no flaming ingredient is present in close proximityto the portion of the electrode from which the arc springs. Although thesame is true to a limited. extent, of electrodes containing smallamounts of flaming material, the presence of flaming material isundesirable because it reduces the temperature of the are stream and theintrinsic b rilliancy.

In the single figure of the drawing I haveshown a method ofaccomplishing the desired result by means of an electrode having acentral pin.

The structure shown in the drawing consists of an outer shell 3 of purecarbon, a central core 4 of graphite or graphitic material and anintermediate filling 5 of pow- 'dered graphite or graphitic mate-rialheld together by a small amount of a carbonaceous binder. The core,which preferably is forced or molded and then baked, is pushed into agreen or unbaked shell filled with the viscous filling of graphiticmaterial and binder. The diameter of the hole in the shell .is preferabltwice that of the core pin, or reater. have found that the core 1sreadiIy centered in the shell if-the filling material consistsof amixture of fine graphite particles with a suitable quantity of coarseparticles. The coarse particles serve to roperly center the pin in theshell and con not the current to the core. During burmng the arc tendsto remain on the graph1te core because the shell and filling burn awaymore rapidly than the more reslstant graphite core, thus permitting itto pro ect from the shell. On account of its central ,location andbecause it projects from .the body of the. electrode, the are morereadily springs therefrom. The filling material burns away more rapidlythan eithr the shell or core, producing a groove 6 around the core.Thistends to prevent the heat from radiating from the core to the 'shelland keeps the core at a high, temperature. The shell of the electrodemay be provided with a copper coating 7 and nickel coating 8, asdescribed. in the patent to Perris, No. 1,241,270, dated Sept. 25, 1917.

- Although I have set forth what I believe 4 is a reasonable explanationof the steadiness of the electrodes, it must be understood that myinvention is not necessarily limited thereto.

Having described 'my invention, what I claim is: J

1. A negative projector electrode consisting of a carbon shell, agraphite core spaced therefrom and an intermediate filling of powderedgraphite held together by a carbonaceous binder.

2. A negative projector electrode consisting of a carbon shell, a formedgraphite core spaced therefrom and an intermediate filling of powderedgraphite held together by a coked carbonaceous binder.

3. A negative projector electrode consisting of a carbon shell, a formedgraphite core spaced therefrom, and an intermediate filling of powderedgraphite, said filler containing a quantity of large graphitic particlesadapted to space the core from the shell.

4. A negative projector electrode consisting of a carbon shell, a formedgraphite core spaced therefrom and an intermediate filling of powderedgraphite held together by a coked carbonaceous binder, said fillerbeingin a more porous condition than the shell or core.

5. A negative projector electrode consisting of e wrbon shell e,corbonnceous core speceol eherefrom, and an intermediate fillin ofpowdered. cnrboneoeous matter, sold 1511 or containing e quantity oflorge conduch- 5 ing moles e opted to spa/2e the core from the shell. v

6. A negwive projector electrode cons1sting' of e carbon shell, ecnrbonoceous in spaoedtherefroxn, and an intermediate 11- ing ofpowdered graphite held together by w e carbonaceous binder. llntestimony whereof, I hereunto affix my signature.

. HOWARD 1B. EYNON.

